Silver sludge that casts into hard, golden ingots

[texassako]

I am almost certain it is zinc contamination from some mystery ingots I melted and repoured since they were varying hardnesses. The oatmeal look just did not sound like my gold tinged crystalline sludge. My little Hot Pot II does not get hot enough to realy melt zinc I believe. As I poured ingots and the lead level lowered, a silver gold crystalline sludge started to form. I did this after I ended up with 3 golden ingots that were very hard, but after those it never seemed liquid enough once I poured the cleaned lead(?) out . I also noticed high surface tension on the melt.

[Fretboard]

do you have any pic's of this sludge

[I'll Make Mine]

The gold color may be overheated tin; if you don't flux enough the tin can separate from the melt. Depending on your alloy composition you may also get a solidus and liquidus from different components melting at different temperatures, which would explain the "sludge" you describe. I doubt this is zinc -- as you note, you'll only get zinc "oatmeal" if you melt the zinc and then start to cool the alloy (allowing the zinc to resolidify as crystals in the melt).

[texassako]

The gold color may be overheated tin; if you don't flux enough the tin can separate from the melt. Depending on your alloy composition you may also get a solidus and liquidus from different components melting at different temperatures, which would explain the "sludge" you describe. I doubt this is zinc -- as you note, you'll only get zinc "oatmeal" if you melt the zinc and then start to cool the alloy (allowing the zinc to resolidify as crystals in the melt).

I did not think it was tin since it is pretty hard, and I have seen tin floating on the top telling me I need to flux it back in to the melt. This is shiny compared to tin, which looks more wrinkly and grey to me. I will get some pics as I have a couple more ingots to seperate.

[texassako]

Here is an ingot of the mystery metal with the gold tint(hard to see in pic) on the sides and the crytalline structure and look is just like what I called sludge.

[texassako]

I now have a pic of the sludge:



I had to get it out of the dross from yesterday, the ingot above may be something else entirely as it melted fine today. The sludge rapidly oxidized today to deep blues and purples, but not yesterday. Could this be antimony or tin coming out of solution since these may have been lino or monotype ingots?

[runfiverun]

those are oxides.
melt them turn the heat up to about 775-f, and use a carbon and fire fluxing to get them back to metal.

[texassako]

The gold color may be overheated tin; if you don't flux enough the tin can separate from the melt. Depending on your alloy composition you may also get a solidus and liquidus from different components melting at different temperatures, which would explain the "sludge" you describe. I doubt this is zinc -- as you note, you'll only get zinc "oatmeal" if you melt the zinc and then start to cool the alloy (allowing the zinc to resolidify as crystals in the melt).

those are oxides.
melt them turn the heat up to about 775-f, and use a carbon and fire fluxing to get them back to metal.

Thanks for the help with a lead for what to search for(tin oxides) and runfiverun's confirmation of what I was starting to think. I started to get decent ingots out of yesterday's dross by using using carbon and lighting the flux, but I could not get enough heat to get it all. Saving the rest for a real smelting session when I find enough scrap lead to mess with. Amazing how a melting session just to blend mystery ingots and cast them into plinking boolits turned into an adventure.

[docone31]

Sometimes within a melt, the metal can grab onto bits of carbon. This acts as an insulator and can prevent further melting of the metal.
If you add some vegetable oil, motor oil, or I have used margerine. When it is done smoking, a large amount of the "cottage cheese" is melted into the majority of the metal.
The carbon bits that are integrated into the metal, acts like scale on the bottom of the pot. It can prevent heat from effectively melting the metal. At least that is what I have found.
I get some real clean melts with vegetable oil.